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	$229.34	11.118%	$254.838	$254.84	$254.85	$254.80
Purchase #2	$101.87	3.816%	$105.7574	$105.76	$105.75	$105.80
Purchase #3	$168.89	11.648%	$188.5623	$188.56	$188.55	$188.60
Purchase #4	$239.96	13.661%	$272.7409	$272.74	$272.75	$272.70
Purchase #5	$51.36	4.369%	$53.6039	$53.60	$53.60	$53.60
Purchase #6	$58.38	7.530%	$62.776	$62.78	$62.80	$62.80
Purchase #7	$128.81	5.522%	$135.9229	$135.92	$135.90	$135.90
7 purchase totals =	$978.61		$1,074.2014	$1,074.20	$1,074.20	$1,074.20