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	$233.68	12.741%	$263.4532	$263.45	$263.45	$263.50
Purchase #2	$229.88	11.676%	$256.7208	$256.72	$256.70	$256.70
Purchase #3	$23.35	9.362%	$25.536	$25.54	$25.55	$25.50
Purchase #4	$12.96	10.516%	$14.3229	$14.32	$14.30	$14.30
Purchase #5	$215.98	10.704%	$239.0985	$239.10	$239.10	$239.10
Purchase #6	$149.92	6.648%	$159.8867	$159.89	$159.90	$159.90
Purchase #7	$222.62	6.609%	$237.333	$237.33	$237.35	$237.30
7 purchase totals =	$1,088.39		$1,196.3511	$1,196.35	$1,196.35	$1,196.30