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	$55.32	9.285%	$60.4565	$60.46	$60.45	$60.50
Purchase #2	$19.92	12.179%	$22.3461	$22.35	$22.35	$22.30
Purchase #3	$240.78	3.788%	$249.9007	$249.90	$249.90	$249.90
Purchase #4	$45.34	11.840%	$50.7083	$50.71	$50.70	$50.70
Purchase #5	$194.81	8.610%	$211.5831	$211.58	$211.60	$211.60
Purchase #6	$104.89	6.279%	$111.476	$111.48	$111.50	$111.50
Purchase #7	$212.51	10.374%	$234.5558	$234.56	$234.55	$234.60
7 purchase totals =	$873.57		$941.0265	$941.04	$941.05	$941.10