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	$232.33	9.512%	$254.4292	$254.43	$254.45	$254.40
Purchase #2	$62.46	10.314%	$68.9021	$68.90	$68.90	$68.90
Purchase #3	$71.79	7.117%	$76.8993	$76.90	$76.90	$76.90
Purchase #4	$172.74	4.556%	$180.61	$180.61	$180.60	$180.60
Purchase #5	$14.31	12.808%	$16.1428	$16.14	$16.15	$16.10
Purchase #6	$185.86	11.311%	$206.8826	$206.88	$206.90	$206.90
Purchase #7	$238.40	7.700%	$256.7568	$256.76	$256.75	$256.80
7 purchase totals =	$977.89		$1,060.6228	$1,060.62	$1,060.65	$1,060.60