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	$203.33	3.630%	$210.7109	$210.71	$210.70	$210.70
Purchase #2	$172.35	5.608%	$182.0154	$182.02	$182.00	$182.00
Purchase #3	$53.33	12.152%	$59.8107	$59.81	$59.80	$59.80
Purchase #4	$87.53	9.552%	$95.8909	$95.89	$95.90	$95.90
Purchase #5	$221.26	11.136%	$245.8995	$245.90	$245.90	$245.90
Purchase #6	$240.93	5.188%	$253.4294	$253.43	$253.45	$253.40
Purchase #7	$91.32	5.290%	$96.1508	$96.15	$96.15	$96.20
7 purchase totals =	$1,070.05		$1,143.9076	$1,143.91	$1,143.90	$1,143.90