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	$48.48	11.217%	$53.918	$53.92	$53.90	$53.90
Purchase #2	$243.75	5.220%	$256.4738	$256.47	$256.45	$256.50
Purchase #3	$246.76	11.668%	$275.552	$275.55	$275.55	$275.60
Purchase #4	$22.77	5.411%	$24.0021	$24.00	$24.00	$24.00
Purchase #5	$67.83	7.419%	$72.8623	$72.86	$72.85	$72.90
Purchase #6	$120.48	12.163%	$135.134	$135.13	$135.15	$135.10
Purchase #7	$183.54	11.416%	$204.4929	$204.49	$204.50	$204.50
7 purchase totals =	$933.61		$1,022.4351	$1,022.42	$1,022.40	$1,022.50