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	$102.25	8.251%	$110.6866	$110.69	$110.70	$110.70
Purchase #2	$234.95	12.582%	$264.5114	$264.51	$264.50	$264.50
Purchase #3	$198.34	6.188%	$210.6133	$210.61	$210.60	$210.60
Purchase #4	$36.94	4.237%	$38.5051	$38.51	$38.50	$38.50
Purchase #5	$32.91	3.162%	$33.9506	$33.95	$33.95	$34.00
Purchase #6	$108.31	11.219%	$120.4613	$120.46	$120.45	$120.50
Purchase #7	$234.61	3.872%	$243.6941	$243.69	$243.70	$243.70
7 purchase totals =	$948.31		$1,022.4224	$1,022.42	$1,022.40	$1,022.50