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	$35.92	3.764%	$37.272	$37.27	$37.25	$37.30
Purchase #2	$121.42	4.783%	$127.2275	$127.23	$127.25	$127.20
Purchase #3	$54.77	13.211%	$62.0057	$62.01	$62.00	$62.00
Purchase #4	$175.37	7.717%	$188.9033	$188.90	$188.90	$188.90
Purchase #5	$106.72	3.476%	$110.4296	$110.43	$110.45	$110.40
Purchase #6	$177.29	7.467%	$190.5282	$190.53	$190.55	$190.50
Purchase #7	$29.86	6.253%	$31.7271	$31.73	$31.75	$31.70
7 purchase totals =	$701.35		$748.0934	$748.10	$748.15	$748.00