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	$97.71	6.613%	$104.1716	$104.17	$104.15	$104.20
Purchase #2	$81.93	7.525%	$88.0952	$88.10	$88.10	$88.10
Purchase #3	$188.40	11.815%	$210.6595	$210.66	$210.65	$210.70
Purchase #4	$165.79	4.113%	$172.6089	$172.61	$172.60	$172.60
Purchase #5	$17.73	3.213%	$18.2997	$18.30	$18.30	$18.30
Purchase #6	$218.25	5.111%	$229.4048	$229.40	$229.40	$229.40
Purchase #7	$203.90	9.645%	$223.5662	$223.57	$223.55	$223.60
7 purchase totals =	$973.71		$1,046.8059	$1,046.81	$1,046.75	$1,046.90