I had the same Wal-Mart dilemma, and here is what helped me (disclaimer: I am the nerd in our house):
I have separate envelopes for groceries, household, personal/toiletries, and dog. At the register, I pay for everything out of the grocery envelope. When I get home, I use the receipt splitter spreadsheet to figure out how to reimburse the other envelopes (I am pretty sure that spreadsheet is in the files).
I check out the deals at www.moneysavingmom.com, www.couponmom.com, and www.hotcouponworld.com before I go shopping to get the best deals on everything by combining coupons and sales. I am getting most of our toiletries, OTC meds, and household products for literally pennies on the dollar using the CVS Extra Care program – it is well worth trying.
This is what has worked for me – hope it’s helpful for you too. Hang in there, and good luck!