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	$35.48	5.437%	$37.409	$37.41	$37.40	$37.40
Purchase #2	$48.36	8.569%	$52.504	$52.50	$52.50	$52.50
Purchase #3	$247.48	7.218%	$265.3431	$265.34	$265.35	$265.30
Purchase #4	$18.58	8.370%	$20.1351	$20.14	$20.15	$20.10
Purchase #5	$241.43	11.684%	$269.6387	$269.64	$269.65	$269.60
Purchase #6	$228.29	7.219%	$244.7703	$244.77	$244.75	$244.80
Purchase #7	$240.56	11.602%	$268.4698	$268.47	$268.45	$268.50
7 purchase totals =	$1,060.18		$1,158.2700	$1,158.27	$1,158.25	$1,158.20