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	$156.51	12.547%	$176.1473	$176.15	$176.15	$176.10
Purchase #2	$69.29	3.437%	$71.6715	$71.67	$71.65	$71.70
Purchase #3	$140.95	13.575%	$160.084	$160.08	$160.10	$160.10
Purchase #4	$131.81	7.495%	$141.6892	$141.69	$141.70	$141.70
Purchase #5	$196.74	9.671%	$215.7667	$215.77	$215.75	$215.80
Purchase #6	$93.54	6.689%	$99.7969	$99.80	$99.80	$99.80
Purchase #7	$184.43	7.419%	$198.1129	$198.11	$198.10	$198.10
7 purchase totals =	$973.27		$1,063.2685	$1,063.27	$1,063.25	$1,063.30