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	$200.33	12.710%	$225.7919	$225.79	$225.80	$225.80
Purchase #2	$14.39	9.461%	$15.7514	$15.75	$15.75	$15.80
Purchase #3	$186.70	4.644%	$195.3703	$195.37	$195.35	$195.40
Purchase #4	$134.44	12.540%	$151.2988	$151.30	$151.30	$151.30
Purchase #5	$240.59	5.255%	$253.233	$253.23	$253.25	$253.20
Purchase #6	$119.89	9.689%	$131.5061	$131.51	$131.50	$131.50
Purchase #7	$152.58	12.700%	$171.9577	$171.96	$171.95	$172.00
7 purchase totals =	$1,048.92		$1,144.9092	$1,144.91	$1,144.90	$1,145.00