Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$187.55	5.698%	$198.2366	$198.24	$198.25	$198.20
Purchase #2	$18.55	12.585%	$20.8845	$20.88	$20.90	$20.90
Purchase #3	$80.85	5.790%	$85.5312	$85.53	$85.55	$85.50
Purchase #4	$132.90	3.188%	$137.1369	$137.14	$137.15	$137.10
Purchase #5	$202.71	13.237%	$229.5427	$229.54	$229.55	$229.50
Purchase #6	$183.94	7.264%	$197.3014	$197.30	$197.30	$197.30
Purchase #7	$215.82	12.413%	$242.6097	$242.61	$242.60	$242.60
7 purchase totals =	$1,022.32		$1,111.2430	$1,111.24	$1,111.30	$1,111.10