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	$175.95	11.650%	$196.4482	$196.45	$196.45	$196.40
Purchase #2	$73.88	11.815%	$82.6089	$82.61	$82.60	$82.60
Purchase #3	$109.70	8.811%	$119.3657	$119.37	$119.35	$119.40
Purchase #4	$54.61	12.642%	$61.5138	$61.51	$61.50	$61.50
Purchase #5	$101.89	8.647%	$110.7004	$110.70	$110.70	$110.70
Purchase #6	$141.52	7.797%	$152.5543	$152.55	$152.55	$152.60
Purchase #7	$180.69	12.538%	$203.3449	$203.34	$203.35	$203.30
7 purchase totals =	$838.24		$926.5362	$926.53	$926.50	$926.50