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	$55.74	10.503%	$61.5944	$61.59	$61.60	$61.60
Purchase #2	$134.26	13.643%	$152.5771	$152.58	$152.60	$152.60
Purchase #3	$115.62	13.226%	$130.9119	$130.91	$130.90	$130.90
Purchase #4	$82.29	4.412%	$85.9206	$85.92	$85.90	$85.90
Purchase #5	$112.60	12.401%	$126.5635	$126.56	$126.55	$126.60
Purchase #6	$248.48	10.842%	$275.4202	$275.42	$275.40	$275.40
Purchase #7	$183.88	3.148%	$189.6685	$189.67	$189.65	$189.70
7 purchase totals =	$932.87		$1,022.6562	$1,022.65	$1,022.60	$1,022.70