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	$219.76	10.705%	$243.2853	$243.29	$243.30	$243.30
Purchase #2	$206.32	9.803%	$226.5455	$226.55	$226.55	$226.50
Purchase #3	$188.53	10.814%	$208.9176	$208.92	$208.90	$208.90
Purchase #4	$87.38	13.535%	$99.2069	$99.21	$99.20	$99.20
Purchase #5	$165.87	13.758%	$188.6904	$188.69	$188.70	$188.70
Purchase #6	$134.28	5.349%	$141.4626	$141.46	$141.45	$141.50
Purchase #7	$55.53	8.860%	$60.45	$60.45	$60.45	$60.50
7 purchase totals =	$1,057.67		$1,168.5583	$1,168.57	$1,168.55	$1,168.60