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	$234.56	5.463%	$247.374	$247.37	$247.35	$247.40
Purchase #2	$67.36	9.476%	$73.743	$73.74	$73.75	$73.70
Purchase #3	$184.82	8.293%	$200.1471	$200.15	$200.15	$200.10
Purchase #4	$82.29	11.294%	$91.5838	$91.58	$91.60	$91.60
Purchase #5	$71.95	8.628%	$78.1578	$78.16	$78.15	$78.20
Purchase #6	$140.78	11.369%	$156.7853	$156.79	$156.80	$156.80
Purchase #7	$100.41	5.527%	$105.9597	$105.96	$105.95	$106.00
7 purchase totals =	$882.17		$953.7507	$953.75	$953.75	$953.80