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	$244.59	7.586%	$263.1446	$263.14	$263.15	$263.10
Purchase #2	$105.89	10.627%	$117.1429	$117.14	$117.15	$117.10
Purchase #3	$199.31	11.444%	$222.119	$222.12	$222.10	$222.10
Purchase #4	$133.58	10.675%	$147.8397	$147.84	$147.85	$147.80
Purchase #5	$231.78	10.663%	$256.4947	$256.49	$256.50	$256.50
Purchase #6	$56.54	7.717%	$60.9032	$60.90	$60.90	$60.90
Purchase #7	$26.30	7.755%	$28.3396	$28.34	$28.35	$28.30
7 purchase totals =	$997.99		$1,095.9837	$1,095.97	$1,096.00	$1,095.80