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	$101.33	7.609%	$109.0402	$109.04	$109.05	$109.00
Purchase #2	$6.63	13.839%	$7.5475	$7.55	$7.55	$7.50
Purchase #3	$199.51	5.782%	$211.0457	$211.05	$211.05	$211.00
Purchase #4	$202.42	10.141%	$222.9474	$222.95	$222.95	$222.90
Purchase #5	$185.55	5.785%	$196.2841	$196.28	$196.30	$196.30
Purchase #6	$213.51	10.317%	$235.5378	$235.54	$235.55	$235.50
Purchase #7	$26.33	4.859%	$27.6094	$27.61	$27.60	$27.60
7 purchase totals =	$935.28		$1,010.0121	$1,010.02	$1,010.05	$1,009.80