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	$60.31	3.699%	$62.5409	$62.54	$62.55	$62.50
Purchase #2	$77.47	7.189%	$83.0393	$83.04	$83.05	$83.00
Purchase #3	$82.59	5.627%	$87.2373	$87.24	$87.25	$87.20
Purchase #4	$89.57	11.293%	$99.6851	$99.69	$99.70	$99.70
Purchase #5	$185.31	3.206%	$191.251	$191.25	$191.25	$191.30
Purchase #6	$86.91	6.603%	$92.6487	$92.65	$92.65	$92.60
Purchase #7	$196.84	11.149%	$218.7857	$218.79	$218.80	$218.80
7 purchase totals =	$779.00		$835.1880	$835.20	$835.25	$835.10