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	$128.35	9.624%	$140.7024	$140.70	$140.70	$140.70
Purchase #2	$132.75	10.406%	$146.564	$146.56	$146.55	$146.60
Purchase #3	$148.43	11.541%	$165.5603	$165.56	$165.55	$165.60
Purchase #4	$185.41	4.425%	$193.6144	$193.61	$193.60	$193.60
Purchase #5	$82.96	4.788%	$86.9321	$86.93	$86.95	$86.90
Purchase #6	$139.27	9.111%	$151.9589	$151.96	$151.95	$152.00
Purchase #7	$136.53	11.362%	$152.0425	$152.04	$152.05	$152.00
7 purchase totals =	$953.70		$1,037.3746	$1,037.36	$1,037.35	$1,037.40