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	$187.30	4.532%	$195.7884	$195.79	$195.80	$195.80
Purchase #2	$42.76	11.368%	$47.621	$47.62	$47.60	$47.60
Purchase #3	$177.89	3.766%	$184.5893	$184.59	$184.60	$184.60
Purchase #4	$128.86	7.668%	$138.741	$138.74	$138.75	$138.70
Purchase #5	$54.51	9.847%	$59.8776	$59.88	$59.90	$59.90
Purchase #6	$172.96	6.515%	$184.2283	$184.23	$184.25	$184.20
Purchase #7	$57.59	6.363%	$61.2545	$61.25	$61.25	$61.30
7 purchase totals =	$821.87		$872.1001	$872.10	$872.15	$872.10