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	$179.38	11.192%	$199.4562	$199.46	$199.45	$199.50
Purchase #2	$149.44	10.756%	$165.5138	$165.51	$165.50	$165.50
Purchase #3	$44.95	11.767%	$50.2393	$50.24	$50.25	$50.20
Purchase #4	$86.95	4.820%	$91.141	$91.14	$91.15	$91.10
Purchase #5	$209.78	6.572%	$223.5667	$223.57	$223.55	$223.60
Purchase #6	$177.35	4.565%	$185.446	$185.45	$185.45	$185.40
Purchase #7	$88.97	6.562%	$94.8082	$94.81	$94.80	$94.80
7 purchase totals =	$936.82		$1,010.1712	$1,010.18	$1,010.15	$1,010.10