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	$167.53	4.780%	$175.5379	$175.54	$175.55	$175.50
Purchase #2	$188.66	5.690%	$199.3948	$199.39	$199.40	$199.40
Purchase #3	$53.37	5.170%	$56.1292	$56.13	$56.15	$56.10
Purchase #4	$139.39	6.331%	$148.2148	$148.21	$148.20	$148.20
Purchase #5	$159.25	6.482%	$169.5726	$169.57	$169.55	$169.60
Purchase #6	$220.74	10.156%	$243.1584	$243.16	$243.15	$243.20
Purchase #7	$56.55	4.146%	$58.8946	$58.89	$58.90	$58.90
7 purchase totals =	$985.49		$1,050.9023	$1,050.89	$1,050.90	$1,050.90