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	$159.89	5.775%	$169.1236	$169.12	$169.10	$169.10
Purchase #2	$10.37	4.352%	$10.8213	$10.82	$10.80	$10.80
Purchase #3	$192.96	13.764%	$219.519	$219.52	$219.50	$219.50
Purchase #4	$94.82	4.529%	$99.1144	$99.11	$99.10	$99.10
Purchase #5	$236.88	7.553%	$254.7715	$254.77	$254.75	$254.80
Purchase #6	$102.82	8.190%	$111.241	$111.24	$111.25	$111.20
Purchase #7	$133.39	3.810%	$138.4722	$138.47	$138.45	$138.50
7 purchase totals =	$931.13		$1,003.0630	$1,003.05	$1,002.95	$1,003.00