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	$58.52	4.785%	$61.3202	$61.32	$61.30	$61.30
Purchase #2	$12.44	5.778%	$13.1588	$13.16	$13.15	$13.20
Purchase #3	$184.67	6.593%	$196.8453	$196.85	$196.85	$196.80
Purchase #4	$181.90	11.862%	$203.477	$203.48	$203.50	$203.50
Purchase #5	$163.66	5.238%	$172.2325	$172.23	$172.25	$172.20
Purchase #6	$248.54	8.139%	$268.7687	$268.77	$268.75	$268.80
Purchase #7	$229.97	10.621%	$254.3951	$254.40	$254.40	$254.40
7 purchase totals =	$1,079.70		$1,170.1976	$1,170.21	$1,170.20	$1,170.20