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	$100.76	4.345%	$105.138	$105.14	$105.15	$105.10
Purchase #2	$123.48	3.299%	$127.5536	$127.55	$127.55	$127.60
Purchase #3	$196.87	3.489%	$203.7388	$203.74	$203.75	$203.70
Purchase #4	$200.44	13.556%	$227.6116	$227.61	$227.60	$227.60
Purchase #5	$161.81	12.713%	$182.3809	$182.38	$182.40	$182.40
Purchase #6	$72.56	13.154%	$82.1045	$82.10	$82.10	$82.10
Purchase #7	$156.67	7.499%	$168.4187	$168.42	$168.40	$168.40
7 purchase totals =	$1,012.59		$1,096.9461	$1,096.94	$1,096.95	$1,096.90