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	$183.42	7.189%	$196.6061	$196.61	$196.60	$196.60
Purchase #2	$210.47	5.744%	$222.5594	$222.56	$222.55	$222.60
Purchase #3	$19.70	6.866%	$21.0526	$21.05	$21.05	$21.10
Purchase #4	$235.26	13.454%	$266.9119	$266.91	$266.90	$266.90
Purchase #5	$88.44	9.275%	$96.6428	$96.64	$96.65	$96.60
Purchase #6	$236.77	11.761%	$264.6165	$264.62	$264.60	$264.60
Purchase #7	$223.89	6.696%	$238.8817	$238.88	$238.90	$238.90
7 purchase totals =	$1,197.95		$1,307.2710	$1,307.27	$1,307.25	$1,307.30