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	$30.64	5.189%	$32.2299	$32.23	$32.25	$32.20
Purchase #2	$58.43	5.350%	$61.556	$61.56	$61.55	$61.60
Purchase #3	$78.93	9.356%	$86.3147	$86.31	$86.30	$86.30
Purchase #4	$159.96	3.387%	$165.3778	$165.38	$165.40	$165.40
Purchase #5	$230.57	10.103%	$253.8645	$253.86	$253.85	$253.90
Purchase #6	$235.83	6.543%	$251.2604	$251.26	$251.25	$251.30
Purchase #7	$161.40	8.539%	$175.1819	$175.18	$175.20	$175.20
7 purchase totals =	$955.76		$1,025.7852	$1,025.78	$1,025.80	$1,025.90