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	$198.73	11.795%	$222.1702	$222.17	$222.15	$222.20
Purchase #2	$191.37	9.591%	$209.7243	$209.72	$209.70	$209.70
Purchase #3	$247.66	3.562%	$256.4816	$256.48	$256.50	$256.50
Purchase #4	$87.80	13.220%	$99.4072	$99.41	$99.40	$99.40
Purchase #5	$81.88	5.842%	$86.6634	$86.66	$86.65	$86.70
Purchase #6	$204.90	13.692%	$232.9549	$232.95	$232.95	$233.00
Purchase #7	$53.63	12.581%	$60.3772	$60.38	$60.40	$60.40
7 purchase totals =	$1,065.97		$1,167.7788	$1,167.77	$1,167.75	$1,167.90