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	$190.64	11.490%	$212.5445	$212.54	$212.55	$212.50
Purchase #2	$196.50	3.636%	$203.6447	$203.64	$203.65	$203.60
Purchase #3	$13.72	3.180%	$14.1563	$14.16	$14.15	$14.20
Purchase #4	$196.52	11.534%	$219.1866	$219.19	$219.20	$219.20
Purchase #5	$57.67	6.144%	$61.2132	$61.21	$61.20	$61.20
Purchase #6	$220.89	10.253%	$243.5379	$243.54	$243.55	$243.50
Purchase #7	$56.93	11.614%	$63.5419	$63.54	$63.55	$63.50
7 purchase totals =	$932.87		$1,017.8251	$1,017.82	$1,017.85	$1,017.70